Is it a coincidence that the word "ray" sounds like the beginning of "radiation"?

And Radium - The origin of the name comes from the Latin word radius meaning ray

Wonder no more.

From google "etymology", "radiation"

https://www.etymonline.com/word/radiation

radiation (n.)
mid-15c., "act or process of radiating," from Middle French radiation and directly from Latin radiationem (nominative radiatio) "a shining, radiation," noun of action from past participle stem of radiare "to beam, shine, gleam; make beaming," from radius "beam of light; spoke of a wheel" (see radius). Meaning "rays or beams emitted" is from 1560s. Meaning "divergence from a center" is 1650s.

Ray is derived from Latin radius. The verb form 'radio' means to broadcast, as in throwing seeds by hand.

Huh? No... ray rhymes with grey. Radiation rhymes with grad, like graduation. That is why the unit of measure is "rad's" and not "raids".